Well, after some testing on the bench, it looks like with my 1/4" wide by 1/4" diameter drum I get about 8" travel from one shoulder to the other. I'm using a heavy thread for cable. If it is simple math/ratio I'm going to need about a 1" wide drum. Hum, need to look at the dock and see if I'm gona like that? Not sure if the leverage on the end is going to be a problem? Would need to mount it in a carrier bracket.

Never one to slow down...how about this idea? The belt will drive the secondary drum and should slip enough to account for uneven drum speed due to line stacking. (One direction anyway, might not work going the other way?)

Would need to build a frame to hold both drums, but that should be easy.

I was hoping that the taper on the two belt pulleys would cause the drive belt to shift from one side to the other side when the direction changes. What actually happens is the belt (rubber band) walks to one side and stays there no matter the direction of rotation.

I was going to use this setup to give alternating speed to the cable drums for each direction. That way I could go to two drums instead of one, and the slack issue would be managed by the taper drums.

If it worked, I was going to use a longer shaft on each axel and drive the cable drums from the extensions.

Jim- what you have seems to work pretty well. If you need more travel just make a longer drum and support the outer end. The-2-drum idea? I think that will be trouble-(just my opinion). I always say when building use the K.I.S.S. method Enjoying watching your work and I am sure you are learning as you go. Have fun.

Jim, have you considered using a chain drive, driven by the servo? Continuous operation, in either direction, no tracking issues, and you could probably mount a cam to the chain to engage a dog on the barge, to pull or push where you want it. Might be a little more reliable and simpler. It may not be the scale look you are after though..? There is some pretty small and light chain you could use, with sprockets designed to bolt right to a servo output shaft. Couldn't be easier. Just use a simple method (idler sprocket) to keep your chain tight, and you're good to go!

Ya, I was thinking about that yesterday as a matter of fact. I actually already have some chain and two servo heads from servo city. I may try that at some point. I wish I could find some smaller chain, I remember some bent wire stuff from an old clock or something from my boyhood tinkering days...

For those of you still following along, here is a picture I found from a company that makes the full scale systems.

The Wintech Uni-Move System is a single winch system in which cables exit the winch in both directions. This type of system is commonly referred to as a continuous loop or one rope on/one rope off system. Uni-Move is available with both single speed and variable speed drives. The winch drum is grooved and is designed to accommodate the total shuttle travel of the barge. Total travel distance in a continuous loop system is limited to the length of cable contained in a single layer.

Note where at the end they state the total available travel is limited to the single wrap cable length. " I could have told em that."

Hey Jim have you thought about using 2 drums on your winch and connecting a rubber band or small spring to pick up any slack or tension .This could be added mid point of your tow line .might be worth a try

What if the cable didnt have to wrap all the way around the drum. It should not take much force at all to move the barges. If you built it like a basic rope tow at a ski resort you wouldnt have the problem with the calbe walking on the drum. Put a large traction wheel on the motor with smaller pullys below it on both sides. The cable is fed in below the small pulley, around the traction wheel and back out under the other small pulley. You could even spring load the pulleys to maintain tension.

That was a great idea! I should try to find some smaller tires and wheels so the speed is a bit slower. I also need to clean up the dock, move the eyes out to the ends of the dock, and I will drill directly to the top of the dock instead of my temp blocks. And fasten the winch motor down. Probably move the motor to one end of the dock.

Glad I could help. That works really well. Your right a smaller tire would do the trick. Dont count on me offering up another good idea for a long time, one per year is about all I am good for. As I have said before, I appreciate you sharing with us. Your pond and creations are awesome. With the new babies, this forum is the only involvement I have time for in this great hobby.

Jim-I think you got it! Looks perfect to me. Is your motor set-up waterproof or is it portable so you can get it out of the weather. Do you know how long it takes to load-1-barge with the conveyor? Nice job!

Thanks. The motor would probably be ok in the rain. I'm planning to build a simple little shed to put over it mostly for looks. The way it turned out, the bracket the motor and wheels are attached to is sprung just a bit and simply slides in between the two angle brackets that are bolted down to the concrete. So, it is simply lift out, no tools required.

I think it is about 1/3 faster loading with the conveyor, from 15 minutes down to 10. May be a bit better now with the dock winch. I should build a silo to store sand and another conveyor. It would be neat to get the conveyor running full load, I'll bet it would load a barge in five minutes or less if the silo was full and held at least a barge load of sand.

The silo would be a nice addition to your "mini diorama". I noticed on one of the loading videos that you were having a hard time with the dragline keeping up with the conveyor. Just need more practice . Or perhaps a larger collector on the conveyor that you could fill before starting it and maybe then the dragline could keep up. Just a suggestion, you are doing a great job. I am a "water nut" and if I had this set-up 20yrs. ago you would have never got me away from the site.